Are there actually special rules for DL ships in combat?

I've noticed they're appear to be much more likely to receive 0 damage than ship stats would indicate.

For example.

DL escort has ridiculous attack and 16 beam defence.

Three medium ships with 12 missile attack go after this escort one-by-one. However, 2 out of the 3 do NO damage while the 3rd knocks off grand 2 points (out of 11) ..

Expected result should be that the ATTACK is 0-12 and the DEFENCE is SQRT(16) = 0-4 points ..

I did some statistical analysis and came up with this projected results for 1 round of combat:

Damage Frequency
0 2293 22,9 %
1 799 8,0 %
2 750 7,5 %
3 800 8,0 %
4 777 7,8 %
5 760 7,6 %
6 793 7,9 %
7 782 7,8 %
8 792 7,9 %
9 577 5,8 %
10 443 4,4 %
11 283 2,8 %
12 150 1,5 %

So in other words, you have 23% chance of doing 0 damage with each ship. So far so good, but 2 consecutive 0 damages would add up to 0.229 * 0.229 = 0.052 or 5,2% .. Not so tall odds. No, I'm not basing this just on isolated incident. It's constant carnage with almost no damage dealt if you send lone ships after DLs whatever the numbers would suggest.

What's more, when I group the 3 ships into a fleet, the damage starts to work like you'd expect! Even when your fleet gets wiped out, DL ship takes damage.

Perhaps there's bad random number seed or somesuch that tends to roll you 0 on 1st turn on 1vs1 going against DLs?

In vanilla GC2 it was futile to send just ONE ship against DLs, while TWO ships had almost 100% result rate.